/* $OpenBSD: mkpar.c,v 1.18 2014/03/13 00:59:34 tedu Exp $	 */
/* $NetBSD: mkpar.c,v 1.4 1996/03/19 03:21:39 jtc Exp $	 */

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Robert Paul Corbett.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "defs.h"

action **parser;
int SRtotal;
int SRexpect = 0;
int RRtotal;
short *SRconflicts;
short *RRconflicts;
short *defred;
short *rules_used;
short nunused;
short final_state;

static int SRcount;
static int RRcount;

extern action *parse_actions();
extern action *get_shifts();
extern action *add_reductions();
extern action *add_reduce();

short sole_reduction(int);
void free_action_row(action *);

void find_final_state(void);
void unused_rules(void);
void remove_conflicts(void);
void total_conflicts(void);
void defreds(void);


void
make_parser(void)
{
	int i;

	parser = NEW2(nstates, action *);
	for (i = 0; i < nstates; i++)
		parser[i] = parse_actions(i);

	find_final_state();
	remove_conflicts();
	unused_rules();
	if (SRtotal + RRtotal > 0)
		total_conflicts();
	defreds();
}


action *
parse_actions(int stateno)
{
	action *actions;

	actions = get_shifts(stateno);
	actions = add_reductions(stateno, actions);
	return (actions);
}


action *
get_shifts(int stateno)
{
	action *actions, *temp;
	shifts *sp;
	short *to_state;
	int i, k;
	int symbol;

	actions = 0;
	sp = shift_table[stateno];
	if (sp) {
		to_state = sp->shift;
		for (i = sp->nshifts - 1; i >= 0; i--) {
			k = to_state[i];
			symbol = accessing_symbol[k];
			if (ISTOKEN(symbol)) {
				temp = NEW(action);
				temp->next = actions;
				temp->symbol = symbol;
				temp->number = k;
				temp->prec = symbol_prec[symbol];
				temp->action_code = SHIFT;
				temp->assoc = symbol_assoc[symbol];
				actions = temp;
			}
		}
	}
	return (actions);
}

action *
add_reductions(int stateno, action * actions)
{
	int i, j, m, n;
	int ruleno, tokensetsize;
	unsigned *rowp;

	tokensetsize = WORDSIZE(ntokens);
	m = lookaheads[stateno];
	n = lookaheads[stateno + 1];
	for (i = m; i < n; i++) {
		ruleno = LAruleno[i];
		rowp = LA + i * tokensetsize;
		for (j = ntokens - 1; j >= 0; j--) {
			if (BIT(rowp, j))
				actions = add_reduce(actions, ruleno, j);
		}
	}
	return (actions);
}


action *
add_reduce(action * actions, int ruleno, int symbol)
{
	action *temp, *prev, *next;

	prev = 0;
	for (next = actions; next && next->symbol < symbol; next = next->next)
		prev = next;

	while (next && next->symbol == symbol && next->action_code == SHIFT) {
		prev = next;
		next = next->next;
	}

	while (next && next->symbol == symbol &&
	    next->action_code == REDUCE && next->number < ruleno) {
		prev = next;
		next = next->next;
	}

	temp = NEW(action);
	temp->next = next;
	temp->symbol = symbol;
	temp->number = ruleno;
	temp->prec = rprec[ruleno];
	temp->action_code = REDUCE;
	temp->assoc = rassoc[ruleno];

	if (prev)
		prev->next = temp;
	else
		actions = temp;

	return (actions);
}


void
find_final_state(void)
{
	int goal, i;
	short *to_state;
	shifts *p;

	p = shift_table[0];
	to_state = p->shift;
	goal = ritem[1];
	for (i = p->nshifts - 1; i >= 0; --i) {
		final_state = to_state[i];
		if (accessing_symbol[final_state] == goal)
			break;
	}
}


void
unused_rules(void)
{
	int i;
	action *p;

	rules_used = calloc(nrules, sizeof(short));
	if (rules_used == NULL)
		no_space();

	for (i = 0; i < nstates; ++i) {
		for (p = parser[i]; p; p = p->next) {
			if (p->action_code == REDUCE && p->suppressed == 0)
				rules_used[p->number] = 1;
		}
	}

	nunused = 0;
	for (i = 3; i < nrules; ++i)
		if (!rules_used[i])
			++nunused;

	if (nunused) {
		if (nunused == 1)
			fprintf(stderr, "%s: 1 rule never reduced\n", __progname);
		else
			fprintf(stderr, "%s: %d rules never reduced\n", __progname,
				nunused);
	}
}


void
remove_conflicts(void)
{
	int i;
	int symbol;
	action *p, *pref = NULL;

	SRtotal = 0;
	RRtotal = 0;
	SRconflicts = NEW2(nstates, short);
	RRconflicts = NEW2(nstates, short);
	for (i = 0; i < nstates; i++) {
		SRcount = 0;
		RRcount = 0;
		symbol = -1;
		for (p = parser[i]; p; p = p->next) {
			if (p->symbol != symbol) {
				pref = p;
				symbol = p->symbol;
			} else if (i == final_state && symbol == 0) {
				SRcount++;
				p->suppressed = 1;
			} else if (pref->action_code == SHIFT) {
				if (pref->prec > 0 && p->prec > 0) {
					if (pref->prec < p->prec) {
						pref->suppressed = 2;
						pref = p;
					} else if (pref->prec > p->prec) {
						p->suppressed = 2;
					} else if (pref->assoc == LEFT) {
						pref->suppressed = 2;
						pref = p;
					} else if (pref->assoc == RIGHT) {
						p->suppressed = 2;
					} else {
						pref->suppressed = 2;
						p->suppressed = 2;
					}
				} else {
					SRcount++;
					p->suppressed = 1;
				}
			} else {
				RRcount++;
				p->suppressed = 1;
			}
		}
		SRtotal += SRcount;
		RRtotal += RRcount;
		SRconflicts[i] = SRcount;
		RRconflicts[i] = RRcount;
	}
}


void
total_conflicts(void)
{
	/* Warn if s/r != expect or if any r/r */
	if ((SRtotal != SRexpect) || RRtotal) {
		if (SRtotal == 1)
			fprintf(stderr, "%s: %s finds 1 shift/reduce conflict\n",
				input_file_name, __progname);
		else if (SRtotal > 1)
			fprintf(stderr, "%s: %s finds %d shift/reduce conflicts\n",
				input_file_name, __progname, SRtotal);
	}
	if (RRtotal == 1)
		fprintf(stderr, "%s: %s finds 1 reduce/reduce conflict\n",
			input_file_name, __progname);
	else if (RRtotal > 1)
		fprintf(stderr, "%s: %s finds %d reduce/reduce conflicts\n",
			input_file_name, __progname, RRtotal);
}


short
sole_reduction(int stateno)
{
	int count;
	short ruleno;
	action *p;

	count = 0;
	ruleno = 0;
	for (p = parser[stateno]; p; p = p->next) {
		if (p->action_code == SHIFT && p->suppressed == 0)
			return (0);
		else if (p->action_code == REDUCE && p->suppressed == 0) {
			if (ruleno > 0 && p->number != ruleno)
				return (0);
			if (p->symbol != 1)
				++count;
			ruleno = p->number;
		}
	}

	if (count == 0)
		return (0);
	return (ruleno);
}


void
defreds(void)
{
	int i;

	defred = NEW2(nstates, short);
	for (i = 0; i < nstates; i++)
		defred[i] = sole_reduction(i);
}

void
free_action_row(action * p)
{
	action *q;

	while (p) {
		q = p->next;
		free(p);
		p = q;
	}
}

void
free_parser(void)
{
	int i;

	for (i = 0; i < nstates; i++)
		free_action_row(parser[i]);

	free(parser);
}
